ML20076M635
| ML20076M635 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/01/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20076M633 | List: |
| References | |
| NUDOCS 9411080164 | |
| Download: ML20076M635 (5) | |
Text
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. UNITED STATES NUCLEAR REGULATORY COMMISSION f
WASHINGTON, D.C. 20566-0001
.....,[
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 178 TO FACILITY OPERATING LICENSE NO. DPR-69
[
BALTIM0RE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT. UNIT-NO. 2 DOCKET N0. 50-318-
1.0 INTRODUCTION
By letter dated May 27, 1994, the Baltimore Gas and Electric Company (the licensee /BG&E) submitted a request for' changes to the Calvert Cliffs Nuclear-Power Plant, Unit No. 2, Technical-Opecifications (TSs). The requested changes would revise the pressure-teniperature (P-T) -limits.and extend the applicable, period of the current, P-T' limits from a neutron fluence of 1.92E19 neutron /cm to 4.0E19 neutron /cm at the inside surface of the reactor vessel.
In addition, changes were requested for the. low temperature overpressure protection system-(LTOP) TSs.
2.0 BACKGROUND
The staff evaluates the P-T limits based on the following NRC regulations'and guidance: Appendix G to 10 CFR Part 50; Generic Letters;(GLs) 88-11 and 92-01; Regulatory Guide (RG) 1.99, Rev. 2; and Standard Review Plan (SRP) Section
~5.3.2.
Appendix G to 10 CFR Part 50 requires that P-T limits for the reactor vessel.must be at least as conservative as those obtained by Appendix G to-Section III of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). Consistent with GL 88-11, licensees use the-methods in RG 1.99, Rev. 2, to predict the effect of neutron irradiation by-calculating adjusted reference temperature (ART) of reactor vessel materials.
The ART is defined as the sum of initial nil-ductility transition reference temperature (RT,) of the material, the increase in RT
- caused by neutron irradiation,anTamargintoaccountforuncertainties1ntheprediction-method. The increase in RT is calculated from the product of a chemistry ng factor and a fluence factor. t The chemistry factor is dependent upon the amount of copper and nickel in the vessel material. Consistent with GL 92-01, licensees submit reactor vessel materials data, which the staff will use in the review of the P-T limits submittals.
SRP 5.3.2 provides guidance on calculation of the P-T limits using linear elastic fracture mechanics methodology specified in Appendix G to Section III of the ASME Code.
In relation to the requested changes in the LTOP system, the original LTOP systemwasapprovedfor10effectivefullpoweryears(QPYs)aandwasextgded to 13.8 EFPYs with a peak fluence revision from 1.69x10 n/cm to 1.92x10 9411080164 941101 PDR ADOCK 05000318 P
8
, 2 n/cm based on the revised chemistry for the reactor vessel welds 2-203-A, B, and C.
With this revision, plate D-8906-1 became the critical element. The weld 2-203-A, B and C chemistry revision was approved by the NRC in its letter to BG&E, dated May 24, 1993.
The present license amendment request describes modifications for continued LTOP protection to 30 EFPYs. The specified P-T limits comply with the requirements of Appendix G to 10 CFR Part 50. This is to be accomplished by:
- 1) implementation of a variable LTOP Power operated relief valve (PORV) setpoint system, as has been already approyed anj implemented on Unit 1;
- 2) accounting for a peak fluence of 4.0x10 ' n/cm ; 3) decreasing the temperature measurement uncertainty;
- 4) lowering the rate of temperature change in the reactor vessel and;
- 5) lowering the rango during which the high pressure safety injection (HPSI) pumps are put into normal operation on cooldown and returned to the automatic mode during heatup.
3.0 EVALUATION For the Unit 2 reactor vessel, BG&E determined that base plate, D-8906-1, is the limiting material.
For the plate, BG&E calculated an ART of 177.1 'F at the 1/4T location (T - the thickness of the reactor vessel at the beltline region) ared an ART of 146.8 'F at the 3/4T location.
The staff performed an independent calculation of the ART values for plate D-8906-1 using RG 1.99, Revision 2.
The staff used a chemical composition of 0.15% copper and 0.56% nickel and an initial RT,taff calculated ARTS of of 10 *F that the licensee had reported for the plate under GL 92-01. The s 177'Fand147' Fat 1/4Tand3/4T1pcations,respectively,usingtheproposed neutron fluence of 4.0E19 neutron /cm Based on the staff's calculation, the staff verified that the licensee's calculated ARTS are acceptable.
Subecituting limiting ARTS of 177 'F and 147 'F into equations in SRP 5.3.2, the -taff verified that the proposed P-T limits for heatup, cooldown, e i- :ality, and iraervice hydrostatic testing satisfy the requirements in N. graphs IV.A.2 & IV.A.3 of Appendix G of 10 CFR Part 50.
In addition to beltline materials,. Appendix G of 10 CFR Part 50 also imposes a minimum temperature at the closure head flange based on the reference temperature for the flange material.
Section IV.A.2 of Appendix G states that when the pressure exceeds 20% of the preservice system hydrostatic test pressure, the temperature of the chsure flange regions highly stressed by the bolt preload must exceed the reference temperature of the material in those regions by at least 120 *F for normal operation and by 90 *F for hydrostatic pressure tests and leak tests.
Based on the flange RT of 10 *F provided by BG&E, the staff has determined that the proposed P-T N mits have satisfied the requirement for the closure
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flangrregionlduring nor9al operation, hydrostatic pressure testing, and leakL testing.
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3.1 Limitina Element Fluence l
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-For play D-8t06-1, the gst neutron fluence (E>1.0 MeV) was increased;from 1,92x10 n/ca' to 4.0x10 n/cm which corresponds;to more than 30 EFPYs of
.i operation. The increased value is based'on the results of' surveillance capsule _97* report BAW-2199. Review of this report -indicated that.the method i
of fluence. estimation complies with staff recommendations and that the 1
measured value is consistent with.. analytical = predictions.
~Therefore,assumingthatfuelloadingsforCycle~10andsubsequent~cyclespave' i
neutron leakages ' bounded by that of Cycle.10, the assumed value of 4.0x10' s
-n/cm' to 30 EFPYs, is conservative and therefore, is acceptable.
e 3.2-Variable LTOP System l
A digital PORV actuation system will be. implemented to provide a variable PORV trip setpoint during low temperature operation. The system retains the single.
.PORV setpoint during shutdown cooling operations. This system is the same as the one approved for Unit.1,.and is, therefore, acceptable.
1 3.3 Minimum Enable Temperature
]
The increased fluence will increase
' minimum enable temperature, yet this t
increase will.be more than offset by a decrease in the heatup rate (60 *F/hr from 75 *F/hr).and a decrease in the temperature. uncertainty from'10 *F.-to-6 *F..The proposed minimum enable temperature is 301 *F versus 305 *FJ The proposed temperature range for the HPSI to be placed on manual control on a cooldown and returned to automatic on heatup.is 301. *F to 325 *F' versus' 305. 'F.
to 350 *F.
Based on BG&E's statements that:. (1) calculations show that the new range allows more'than 10 minutes for.the operator to manually start a HPSI pump and
. prevent core damage in case of a LOCA. (2) that the new range of 24 *F.is.
l
. comparable to the 20 *F for Unit 1 and (3) that the improved uncertainty is a
. result of improved instrumentation, we find the proposed minimum enable temperature and the proposed temperature range to-be acceptable.
3.4 Sinale PORV LTOP Enable Setooint
=!
' To protect the Appendix G limits.at' all temperatures when the reactor is in j
modes 4 or 5, the variable LTOP system has a single setpoint'independeng of i
the7eactorcoolant. system (RCS) temperature. For fluence below 4.0x10 i
n/cm this value is to be set less than or equal to 443 psia.
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i "3.5 Calculational Method i
The. required calculations for the. reactor pressure during a transient were
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estimated using the RELAP5/M003^ code which is. able to model-cordex heat-1 transfer phenomena.- The calculated PORV flows obtained with RELAP were-
' benchmarked against data from the Electric Power Research Institute PORVi.
qualification tests. The use of the RELAP code with.the PORV flow benchmark.
is acceptable.
4.0 ' Reauested Technical Soecification Chanaes Implementation of the above changes requires the following TS change' :
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'TS 3.1.2.1 Boration Systems: Flow Paths - Shutdown, Footnote'*
1 TS 3.1.2.3 Boration Systenis: Charging Pump - Shutdown, Footnote
- i TS 3.4.1.2 Coolant Loops and Coolant Circulation - hot Standby, Footnote **
TS 3.4.1.3 Coolant Loops and Coolant Circulation Shutdown, Footnote ***
TS 3.4.3 Relief Valves, Footnote
- and' Action Statements, b,.'c and d' TS 3.4.9.3 P-T Limits' Overpressure Protection Systems,. Applicability and l
Action Statement a.-
l TS 4.5.2 Emergency Core Cooling System (ECCS)', Surveillance l
Requirements, Footnote
l1 The above TSs change'the RCS temperature limit from 305 *F to 301 *F.
l TS 3.3 Instrumentation Table 3.3-3, Note 9 1
i The limits of RCS temperature for HPSI operability change from:.
i 305.*F - 350 *F to 301 'F - 325 'F~
q TS 3.4.9.1 Pressure / Temperature Limits, Reactor Coolant ' System.- The:
heatup rates change from'75_'F in any one hour (IA0H) to:
30 'F IA0H for RCS. temperature.70 'F to 156 *F-40 'F IA0H for RCS temperature >156 *F to 246 'F-60 *F IA0H for RCS temperature > than 246 *F-The maximum allowat'le cooldown' rate changes:
from to 100*F IA0H for RCS temp.
>180*F
>200*F 1
40*F IA0H for RCS temp.
180'F-140*F 200*F-176*F 15'F IA0H for RCS't'emp.
<140*F
<176*F TS 3.4.9-1 The figures with heaty and,cooldown P-T limits for 3.4.9.2 fluence up to 1.92x10 n/cm
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The figures p're sugstituted with equiv'alent figures for fluence.
up to 4.0x10 n/cm i
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e, TS 3.4.9-3 Pressure / Temperature Limits, Overpressure Protection Limits.
Figure 3.4.9-3 is added.
Figure 3.4.9-3isintroducedtodefinemaximumPgRVopgning pressure vs temperature for fluence up to 4.0x10 n/cm. - In -
addition, the expression " lift. setting" is substituted with the.
expression " trip setpoint". Also, a footnote is added indicating the PORV setpoint is 443 psia when in shutdown cooling.
The TS Bases are updated to reflect the above changes.
These proposed TS changes are consistent with the revised heatup and cooldown rates and RCS P-T limits, as detailed in Section 3.0.of this-Safety Evaluation The proposed TS changes assure that the Appendix G P-T limits will be 2
maintained for neutron fluences less than or equal to 4.0E19 neutrons /cm and are, therefore, acceptable.
5.0 STATE ~ CONSULTATION In accordance with the Commission's regulations, the Maryland State official was notified of the proposed issuance of the amendment. The State official had no comments.
6.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation.or use of a facility component located within the restricted area.as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite,.and that there is no significant increase in individual or cumulative-occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no'significant hazards consideration, and there has been no public comment on such finding (59FR37064). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement-or environmental assessment need be prepared in connection with the issuance of the amendment.
7.0 CONCLUSION
The Commission has concluded, ba's on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the commori defense and security or to the health and safety of the public.
a Principal Contributors: J.Tsao, L.Lois Date:
November 1,1994 i
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